Machine for Exercising the Muscles of the Lower Back and Associated Methods

ABSTRACT

A machine is for exercising the muscles of the lower back. The machine includes a base frame and a resistance arm including a resistance pad engaged by the user, the resistance arm coupled to the base frame at a first rotation point and having a center of rotation about the first rotation point. The machine further includes a seat frame member carrying a seat, the seat frame member coupled to the base frame at one or more seat rotation points and having a center of rotation about each of the seat rotation points. The resistance arm and seat frame member are rotated in opposite directions during a repetition cycle about the respective first rotation point and at least one seat rotation point.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/684,975 filed May 26, 2005, of which is hereby incorporated herein in its entirety by reference.

FIELD OF THE INVENTION

The present invention relates to the field of exercise machines, and, more particularly, to exercise machines for the lower back and related methods.

BACKGROUND OF THE INVENTION

Various exercise machines have been disclosed which exercise the back muscles using a resistance arm in combination with a resistance pad in contact with the back, along with various elements ensuring pelvic isolation. Pelvic isolation is typically achieved by placement of the feet on a foot board, contact of the pelvis to the back of a seat, and downward pressure on the shins and thighs by a knee restraint device. These machines specifically attempt to exercise the lumbar muscles of the lower back, consisting essentially of the lower five vertebrae of the spine.

In U.S. Pat. No. 6,004,246 to Sencil, assigned to the owner of the present application, for example, such a machine is disclosed having a resistance pad mounted to several attached movement arms. A virtual movement arm connected to the center of the resistance pad has a center of rotation located above the seat base and forward from the seat back. A movement arm pivoting at this center of rotation would impede a user from using the machine. Thus, the machine structure features extensive parallel links to the virtual movement arm, mountage links, rods, and pivot pins to position the resistance pad in a rotation path about this center of rotation.

Although the '246 patent discloses a structure for rotating the resistance pad about the center of rotation, the structure involves complicated, large scale construction. Further, the resistance arm of the '246 patent cannot be disengaged for easy adjustment of its initial position prior to the user entering the machine. This may introduce a risk for users with limited range of motion. Thus, it would be advantageous to provide an exercise machine for the back having a relatively simple frame structure and utilizing spatial efficiency. Yet further, it would be advantageous to provide an exercise machine for the back accommodating users of varying flexibility.

SUMMARY OF THE INVENTION

In view of the foregoing background, it is therefore an object of the present invention to provide a machine for exercising the muscles of the lower back. The machine includes a base frame and a resistance arm including a resistance pad engaged by the user. The resistance arm is coupled to the base frame at a first rotation point and has a center of rotation about the first rotation point. The machine may further include a seat frame member carrying a seat, the seat frame member coupled to the base frame at least one seat rotation point. The seat frame member has a center of rotation about each of the at least one seat rotation point. The resistance arm and seat frame member may be rotated in opposite directions during a repetition cycle about the respective first rotation point and at least one seat rotation point.

The seat may include a base and a back for defining a lumbar rotation center (LRC) fixed relative to the seat, the LRC positioned above the base and forward from the back. The resistance pad center of rotation over the repetition cycle may substantially coincide with the LRC.

The radial distance between the resistance pad and the LRC over the repetition cycle may accommodate users of varying size, and the range of the radial distance between the resistance pad and the LRC over the repetition cycle may be minimized.

The base frame may extend the base of the machine and the machine may further include at least one forward link coupling the base frame to the seat frame member adjacent a front area of the machine. Each forward link may include at least one link rotation point, which may include a seat rotation point. Each forward link may include a top end and a bottom end, and a seat rotation point may be adjacent the top end of each forward link. Each forward link may include a rotation point adjacent the bottom end for rotatably connecting the forward link to the base frame.

The first rotation point, at least one seat rotation point and at least one link rotation point are selectively positioned such that the radial distance between the resistance pad and the LRC accommodates users of varying size, and the range of the radial distance between the resistance pad and the LRC over the repetition cycle is minimized. The LRC may correspond to the approximate center of rotation of the lower five vertebrae of a user positioned on the seat.

The resistance pad may engage the upper back of the user. The machine may further include a locking mechanism for selectively adjusting the initial angle of the resistance arm relative to the base frame at the beginning of a repetition cycle. The resistance arm may further include a first end coupled to the resistance pad and a second end coupled to the locking mechanism. The first rotation point of the resistance arm may be positioned between the first and second end of the resistance arm. The locking mechanism may adjust the angular range of the resistance arm during a repetition cycle. The locking mechanism may disengage the machine resistance while adjusting the initial angle of the resistance arm to accommodate users of varying flexibility entering the machine. The locking mechanism may include a hydraulic cylinder.

The seat frame member may include a first end adjacent the seat, a second end coupled to a foot board for mounting the user's feet during operation of the machine, and a first seat rotation point adjacent the second end. The seat frame member may further include a second seat rotation point between the first and second end, along an underside of the seat frame member.

The machine may further include a lifting arm having a first end coupled to the resistance arm first rotation point and a second end rotatably coupled to the second seat rotation point of the seat frame member. The base frame may include a side bar having a first end integral with the base frame and a second end coupled to the first rotation point of the resistance arm and further coupled to the first end of the lifting arm. The base frame may further include a stand for supporting the seat frame member adjacent the second end of the lifting arm prior to beginning the repetition cycle.

The resistance pad may further include a pair of handles coupled to the first end of the resistance arm to be grasped by the user during the repetition cycle.

The machine may further include a knee restraint coupled to the seat frame member for restraining the user's knees and isolating the pelvis while using the machine. The knee restraint may include an adjustable knee bar for adjustably positioning the knee restraint, and a locking device for securing the knee restraint in contact with the user's knees.

A method aspect may include assembling a machine for exercising the muscles of the lower back. The method may include forming a base frame, and rotatably coupling a resistance arm including a resistance pad to be engaged by the user to the base frame at a first rotation point, the resistance arm having a center of rotation about the first rotation point. The method may further include rotatably coupling a seat frame member carrying a seat to the base frame at least one seat rotation point, the seat frame member having a center of rotation about each of the at least one seat rotation point. The resistance arm and seat frame member may be rotated in opposite directions during a repetition cycle about the respective first rotation point and at least one seat rotation point. The seat may include a base and a back for defining a lumbar rotation center (LRC) fixed relative to the seat, the LRC positioned above the base and forward from the back. The resistance pad center of rotation may substantially coincide with the LRC. The radial distance between the resistance pad and the LRC may accommodate users of varying size, and the range of the radial distance between the resistance pad and the LRC over the repetition cycle is minimized.

The base frame may extend the base of the machine and the method may further include coupling a forward link from the base frame to the seat frame member adjacent a front area of the machine. The forward link may include at least one link rotation point, including at least one seat rotation point.

The first rotation point, at least one seat rotation point and at least one link rotation point may be selectively positioned such that the radial distance between the resistance pad and the LRC accommodates users of varying size, and the range of the radial distance between the resistance pad and the LRC over the repetition cycle is minimized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side plan view of a machine with knee restraints removed in accordance with the present invention.

FIG. 2 is a side plan view of the machine in FIG. 1 at an extended stage of the repetition cycle.

FIG. 3 is a schematic diagram of a machine with one forward link rotation point in accordance with the present invention.

FIG. 4 is a schematic diagram of the machine in FIG. 3 at an intermediate stage of the repetition cycle.

FIG. 5 is a schematic diagram of a machine with one forward link rotation point in accordance with the present invention.

FIG. 6 is a schematic diagram of the machine in FIG. 5 at an intermediate stage of the repetition cycle.

FIG. 7 is a schematic diagram of a machine with two forward link rotation points in accordance with the present invention.

FIG. 8 is a schematic diagram of the machine in FIG. 7 at an intermediate stage of the repetition cycle.

FIG. 9 is a side plan view of a machine with knee restraints removed in accordance with the present invention.

FIG. 10 is a side plan view of the machine of FIG. 9 at an intermediate initial position.

FIG. 11 is a side plan view of the machine of FIG. 9 at an extended initial position.

FIG. 12 is a side plan view of a machine with knee restraints removed in accordance with the present invention.

FIG. 13 is a side plan view of the machine in FIG. 12 with the resistance arm shifted to an intermediate initial position.

FIG. 14 is a rear perspective view of a machine with resistance arm handles in accordance with the present invention.

FIG. 15 is a side plan view of a machine with resistance arm handles and knee restraints in accordance with the present invention.

FIG. 16 is a rear perspective view of a machine with resistance arm handles and knee restraints in accordance with the present invention.

FIG. 17 is a side plan view of a machine with resistance arm handles and knee restraints in accordance with the present invention.

FIG. 18 is a front perspective view of a machine with resistance arm handles and knee restraints in accordance with the present invention.

FIG. 19 is a front perspective view of a machine with resistance arm handles and knee restraints in accordance with the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.

Referring to FIGS. 1 and 2, a machine 10 for strengthening back muscles is illustrated without the knee pad apparatus to be discussed below. The machine may include a resistance arm 14 having a resistance pad 12 engaged by the user, the resistance arm 14 with a center of rotation about a first rotation point 13. During the repetition cycle, the user may exert force on the resistance pad 12, thereby causing the resistance arm 14 to rotate about the first rotation point 13. The resistance pad 12 may engage the upper back of the user. The machine 10 may further include a seat 19 having a base 22 and a back 24 for defining a lumbar rotation center (LRC) 26 fixed relative to the seat. The LRC 26 may be positioned above the base 22 and forward from the back 24 of the seat 19. The resistance pad 12 center of rotation may substantially coincide with the LRC 26 over the repetition cycle. The LRC may be empirically derived based upon the center of rotation of the lower five vertebrae (“lumbar muscles”) of a user seated on seat 19, and remain fixed relative to the seat base 22 and back 24.

The machine may further include a seat frame member 18 carrying the seat 19, the seat frame member with a center of rotation about at least one seat rotation point 30, 31, 44. The resistance arm 14 and seat frame member 18 may be rotated in opposite directions during a repetition cycle about the respective first rotation point 13 and at least one seat rotation points 30, 31, 44. The counter rotation of the resistance arm 14 and seat frame member 18 may be such that the radial distance between the resistance pad 12 and the LRC 26 accommodates users of varying size and the range of the radial distance between the resistance pad 12 and the LRC 26 over the repetition cycle is minimized.

The machine 10 may further include a base frame 34 extending the base of the machine and a forward link 28 coupling the base frame to the seat frame member 18 adjacent the front of the machine. The forward link 28 may include at least one link rotation point 30, 32, including a seat rotation point 30. The forward link 28 may include a top end 27 for positioning a seat rotation point 30 and a bottom end 29 for rotatably connecting the forward link to the base frame 34. The forward link 28′ may include a top end 27′ for positioning a seat rotation point 31 and a bottom end 29′ integral with the base frame 34.

The first rotation point 13, at least one seat rotation point 30, 31, 44 and at least one link rotation point 32 may be selectively positioned such that the radial distance between the resistance pad 12 and the LRC 26 accommodates users of varying size and the range of the radial distance between the resistance pad 12 and the LRC 26 over the repetition cycle is minimized.

The machine 10 may further include a locking mechanism 16 for selectively adjusting the initial angle of the resistance arm 14 relative to the base frame 34 at the beginning of a repetition cycle. The resistance arm 14 may further include a first end 11 coupled to the resistance pad 12 and a second end 15 coupled to the locking mechanism 16. The first rotation point 13 of the resistance arm 14 may be located between the first end 11 and second end 15. The locking mechanism 16 may further adjust the angular range of the resistance arm 14 during a repetition cycle. The locking mechanism 16 may disengage the machine resistance to facilitate adjustment of the initial angle of the resistance arm 14 to accommodate users of varying flexibility entering the machine 10.

The locking mechanism 16 may include a hydraulic cylinder. The hydraulic cylinder may operate in compression and use hydraulic fluid to fix position. FIG. 9 illustrates such a hydraulic cylinder locking mechanism 16, attached at the lower end of the resistance arm 14. The hydraulic cylinder locking mechanism 16 may feature a push-button or similar lever which releases the internal hydraulic lock valve 17 and permits the user to move the resistance arm to a continuum of positions while sitting in the seat base 22 or standing beside the machine. FIGS. 9-11 illustrates the hydraulic cylinder locking mechanism 16 in a flexed, intermediate, and extended position, respectively. In the flexed position, a user with above average flexibility can enter the machine 10 without utilizing the locking mechanism 16 and make contact with the resistance pad 12 over the maximum angular range. A user with average flexibility can enter the machine 10 and engage the push-button releasing the lock valve 17 so to disable the machine resistance and move the resistance arm 14 to the intermediate position. The user can alternatively engage the push-button to release the lock valve 17 prior to entering the machine 10. The user can then make contact with the resistance pad 12 over a moderate angular range. Prior to entering the machine 10, a user with low flexibility typically may engage the push-button releasing the lock valve 17 so to disable the machine resistance and move the resistance arm 14 to or near the extended position. After the resistance arm 14 is so positioned, the user then sits in the machine 10 and makes contact with the resistance pad 12 over a narrow angular range. The flexed, intermediate, and extended positions are merely three examples of initial positions of the movement arm 14, and locking mechanism 16 may adjust to a continuum of initial positions between flexed and extended. Numerous other locking mechanisms may be used.

The seat frame member 18 may include a first end 21 adjacent the seat 19, and a second end 23 coupled to a foot board 20 for mounting the user's feet during operation of the machine 10. A first seat rotation point 30,31 may be positioned adjacent the second end 23 of the seat frame member 18. The seat frame member 18 may further include a second seat rotation point 44 between the first 21 and second ends 23, on the underside of the seat frame member.

The machine 10 may further include a lifting arm 40 having a first end 41 rotatably coupled to the resistance arm first rotation point 13 and a second end 43 rotatably coupled to the second seat rotation point 44 of the seat frame member 18. The base frame 34 may include a side bar 38 having a first end 45 integral with the machine base and a second end 47 rotatably coupled to the first rotation point 13 of the resistance arm and further coupled to the first end 41 of the lifting arm. The base frame 34 may further include a stand 36 for supporting the seat frame member 18 adjacent the second end 43 of the lifting arm 40 prior to beginning the repetition cycle. Side bar 38 may connect to lateral bars 35 which laterally stabilize the machine while in use. The second end of the lifting arm 40 may link the locking mechanism 16 to the seat frame member 18, provide an extension 42 for engaging the stand 36 when the machine is in the rested position, and rotatably engage the seat frame member 18 at a seat rotation point 44 for facilitating rotation of the seat frame member 18 about the seat rotation points 30, 44.

FIG. 1 illustrates the machine in the start position, prior to any force placed on the resistance pad 12. The angle between the resistance arm 14 and the base frame 34 is approximately ninety degrees. After force is placed on the resistance pad 12, the resistance arm 14 may rotate counter-clockwise about the resistance arm first rotation point 13, the seat frame member 18 may rotate clockwise about the seat rotation point 30, and the LRC 26 may rise relative to the ground but remain fixed relative to the seat base 22 and back 24. Any structure for providing resistance to the resistance arm 14, including selective resistance, such as a weight stack, for example, may be utilized, as appreciated by one of skill in the art. FIG. 2 illustrates the machine 10 in an extended or near-extended position, or position of maximum rotation of the resistance arm 14 and seat frame member 18.

As shown in FIGS. 1 and 2, the first rotation point 13, or center of rotation of the resistance arm 14, is behind and below the LRC 26. Although the resistance arm's 14 center of rotation does not coincide with the LRC 26, a method for assembling a back exercise machine may permit the resistance pad 12 center of rotation to substantially coincide with the LRC 26. This method assesses the radial distance from the resistance pad 12 to the LRC 26, and the LRC 26 height from the ground over the machine's angular range for a particular arrangement of the machine rotation points 13, 30, 31, and 44. The LRC 26 location may be determined, from its empirically derived fixed relationship relative to the seat base 22 and back 24. Each machine rotation point arrangement includes placement of one or more of the first rotation point 13, seat rotation points 30, 31, 44 and link rotation point 32. A machine design includes rotation point placements achieving proper radial magnitude and minimal range of the radial distance between the resistance pad 12 and LRC 26 over the repetition cycle. Proper radial magnitude permits the machine to accommodate a wide range of users, and minimal radial range permits the resistance pad 12 to maintain contact with substantially the same portion of the users back, without shifting, as appreciated by one of skill in the art. FIGS. 3 and 4 illustrates an initial rotation point design for angles of 90 and 106 degrees between the resistance arm 12 and base bar 34. Note that seat rotation point 31 is distinguished from seat rotation point 30 and link rotation point 32 in FIGS. 1 and 2, as a sole rotation point on the forward link 28 for the seat frame member 18. Table 1 shows the data obtained over the angular range, including the radial distance from the resistance pad 12 to the LRC 26 and the LRC 26 height relative to the ground. The data of Tables 1-3 and illustrated embodiments in FIGS. 3-8 are exemplary and not intended to limit the scope of the embodiments of the invention.

TABLE 1 Layout Center Angle Radius height 90 13.155 18.561 92 12.855 19.177 94 12.637 19.789 96 12.516 20.394 98 12.506 20.99 100 12.616 21.574 102 12.85 22.142 104 13.208 22.694 106 13.683 22.227 108 14.267 23.739 110 14.947 24.228 112 15.71 24.695 114 16.554 25.137 116 17.435 25.555 118 18.371 25.949 120

Seat rotation point 31 is then lowered by shortening forward link 28, first rotation point 13 is raised, and seat frame member 18 is shortened, effectively shifting seat rotation point 44 (See FIG. 1) away from the resistance arm 14. FIGS. 5 and 6 illustrate this new arrangement, and Table shows the corresponding data, with a substantial decrease in the radial magnitude and range over the angular cycle.

TABLE 2 Long2-layout-03-30-05 Center Angle Radius Height 90 11 18.75 92 10.665 19.43 94 10.382 20.112 96 10.169 20.796 98 10.042 21.477 100 10.015 22.154 102 10.1 22.824 104 10.304 23.484 106 10.627 24.134 108 11.066 24.77 110 11.612 25.39 112 12.255 25.993 114 12.983 26.577 116 13.783 27.142 118 120

A final arrangement shows a further raising of the first rotation point 13, replacing seat rotation point 31 with seat rotation point 30 and link rotation point 32, and adding seat rotation point 44. The data in table 3 demonstrates a further improved radial magnitude and range. FIGS. 7 and 8 represent the further improved rotation points for the first rotation point 13, seat rotation point 44, and the seat and link rotation points 30,32.

TABLE 3 layout04-11-05v8 Center Angle Radius Height 90 11.513 19.626 92 11.195 20.248 94 10.967 20.868 96 10.835 21.487 98 10.806 22.101 100 10.881 22.712 102 10.956 23.015 104 11.329 23.916 106 11.691 24.508 108 12.133 25.093 110 12.647 25.67 112 13.226 26.238 114 13.862 26.796

Another embodiment of the machine is shown in FIG. 12 showing a roller 50 at the end of the lifting arm 40′, engaging seat frame member 18′ having a circular cross section for receiving the roller 50. The locking mechanism 16′ may link the lifting arm 40′ to the resistance arm 14′ and may be lengthened or shortened by selector 17′, thus changing the initial angle and angular range of the resistance arm 14′. The resistance arm 14′ may be rotatably connected at its end to side bar 38′, as opposed to resistance arm 14 of FIG. 2 rotatably connected to locking mechanism 16. FIGS. 12 and 13 illustrate the flexed and extended positions of resistance arm 14′ after adjusting selector 17′ of the locking mechanism 16′. The locking mechanism 16′ may alternatively include a rod with selection holes that mates with a remotely actuated spring-loaded pin, and selector 17′, allowing for finite increments of adjustment. The locking mechanism 16′ may alternatively include a friction locking brake similar to a pipe clamp allowing for infinite adjustment. The locking mechanism 16′ may further include a pad lock providing for adjustment of the angular position and range of the resistance arm 14′. Those other elements, not specifically mentioned, are indicated with prime rotation, are similar to those elements described above, and need no further discussion herein.

While the machine 10 includes a resistance pad 12 to engage the user's back during the exercise, handles may be included with the machine to maintain position of the hands and arms in order to keep the form of the exercise consistent and provide stability on the upper back, neck and head. FIG. 14 illustrates a pair of handles 60, 62 which may be connected to a transverse bar 64 coupled to the resistance arm 14. The handles 60, 62 can be adjusted by a telescope mount 66 or by clamping around an axis that allows the handles to rotate toward or away from the user, as appreciated by one of skill in the art. The clamp can be fixed for the position for the user or group of users.

In order to ensure the machine exercises and targets the lumbar muscles of the back, pelvic isolation should be achieved. The feet are firmly placed on the foot boards 20, the subject sits on the seat pad with their pelvis firmly pressed against the seat back 24, and their legs flexed at the knee. The seat back 24 may restrict posterior translation of the user's pelvis and the pressing action of the legs against the foot boards 20 may cause the femurs to force the bottom of the pelvis in a posterior and inferior direction. As shown in FIG. 15, knee restraints 70 may include thigh pads 72 and shin pads 74 connected to a rotatable bar 76, that is mounted on an adjustable knee bar 78, which connects to the seat frame member 18. The rotatable bar 76 angular position is adjustable by a tightener 80. Thus, thigh pads 72 and shin pads 74 are rotatable, allowing them to align with the legs to maintain even force. The location of the thigh pads 72 and shin pads 74 above and below the knees may prevent direct pressure on the knees for persons with injuries and evenly distribute force eliminating harmful shear forces to the knees. An adjuster 82 allows for horizontal shifting and locking of the foot boards 20, to accommodate users of varying size. Similarly, an adjuster 84 allows for vertical shifting and locking of the knee bar 78. The adjusters 82, 84 may consist of a telescoping tube and locking pin, screw mechanism permitting infinite adjustment, or any similar element known to one of skill in the art. The knee restraints 70 are proximal and distal to the knee and apply pressure downward toward the seat frame member 18. The pressure at the knees may cause the leg to act as a toggle mechanism forcing the feet to press more firmly on the foot boards 20 and the femurs to press the bottom of the pelvis more firmly toward the seat base 22 and seat back 24 ensuring pelvic isolation.

The adjusters 82, 84 are selectively adjusted to accommodate each user's size and flexibility. In order to effectively and safely apply force to the legs at the knees, the knee restraint adjuster 84 may be adjustable in small increments relative to the seat frame member 18. The knee restraint 70 may be capable of adjustment toward and away from the pelvis pad 24 and toward and away from the seat pad 22. Further, the knee restraint adjuster 84 top range includes allowing the user easy entry and exit from the machine. The knee restraint adjuster 84 also can be locked when the machine is not in use to prevent injuries.

FIGS. 16 and 17 illustrate a knee restraint 70′ having a knee bar 78′ rotatably connected to the center of the foot board 20. A knee restraint safety lock 90 ensures that the knee restraint 70′ does not tip over while in the upright position and not in use. The user sits in the machine, disengages the safety lock 90, rotates the knee bar 78′ down, adjusts knee restraint adjuster 84′ and fastens the hook and belt component 92 with a buckle 94 having length adjustment. A cam-over handle 96 may provide further tightening to achieve high-pressure of the knee pads 70′ to achieve pelvic isolation.

FIGS. 18 and 19 illustrate a knee restraint 70″ having a knee bar 78′ rotatably connected to the center of the foot board 20. An adjustable hydraulic cylinder 100 similar to the locking mechanism 16 features a push-button releasing the lock valve 102 that upon engagement permits rotation of the knee bar 78″. Since the hydraulic cylinder 100 locks in all positions, whether at the top or bottom of the angular range of the knee bar 78″, no safety lock is required. The user engages the push-button releasing the lock valve 102 until a sufficient level of force is placed on the thighs and shins so to achieve proper pelvic isolation. Knee restraint adjuster 84′ provides additional fastening of knee pads 70″. If additional tightening force is desired, a cam-over device 96″ could be used in conjunction with the pivoting support, locking cylinder and pads.

A lap belt similar to a seat belt may be added to all versions of the machine to add another degree of pelvic isolation. The belt may be comfortable with enough width to spread the force that the exerciser could generate during exertion. The belt may pull the pelvis down and back toward the pelvic pad and seat pad. Any belt known to one of skill in the art could be used.

A method aspect may include assembling a machine 10 for exercising the muscles of the lower back. The method may include forming a base frame 34, and rotatably coupling a resistance arm 14 including a resistance pad 12 to be engaged by the user to the base frame at a first rotation point 13, the resistance arm 14 having a center of rotation about the first rotation point 13. The method may further include rotatably coupling a seat frame member 18 carrying a seat 19 to the base frame 34 at least one seat rotation point 30, 31, 44, the seat frame member having a center of rotation about each of the at least one seat rotation point. The resistance arm 14 and seat frame member 18 may be rotated in opposite directions during a repetition cycle about the respective first rotation point 13 and at least one seat rotation point 30,31,44. The seat 19 may include a base 22 and a back 24 for defining a lumbar rotation center (LRC) 26 fixed relative to the seat, the LRC positioned above the base and forward from the back. The resistance pad 12 center of rotation may substantially coincide with the LRC 26.

The base frame 34 may extend the base of the machine and the method may further include coupling a forward link 28 from the base frame to the seat frame member 18 adjacent a front area of the machine 10. The forward link 28 may include at least one link rotation point 30,32, including at least one seat rotation point 30.

Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed. 

1. A machine for exercising the muscles of the lower back, comprising: a base frame; a resistance arm including a resistance pad engaged by the user, the resistance arm coupled to the base frame at a first rotation point and having a center of rotation about said first rotation point; a seat frame member carrying a seat, the seat frame member coupled to the base frame at least one seat rotation point and having a center of rotation about each of said at least one seat rotation point; said resistance arm and seat frame member rotated in opposite directions during a repetition cycle about the respective first rotation point and at least one seat rotation point.
 2. The machine according to claim 1, wherein the seat includes a base and a back for defining a lumbar rotation center (LRC) fixed relative to the seat, the LRC positioned above the base and forward from the back; and wherein the resistance pad center of rotation substantially coincides with the LRC.
 3. The machine according to claim 2, wherein the radial distance between the resistance pad and the LRC accommodates users of varying size, and the range of said radial distance between the resistance pad and the LRC over the repetition cycle is minimized.
 4. A machine according to claim 2, wherein the base frame extends the base of the machine; and further comprising at least one forward link coupling the base frame to the seat frame member adjacent a front area of the machine; said at least one forward link comprising at least one link rotation point, including at least one of said at least one seat rotation point.
 5. A machine according to claim 4, wherein said at least one forward link comprises a top end and a bottom end, and wherein the one of said at least one seat rotation point is adjacent the top end of the at least one forward link.
 6. A machine according to claim 5, wherein said at least one forward link includes a rotation point adjacent the bottom end for rotatably connecting the at least one forward link to the machine base.
 7. A machine according to claim 6, wherein the first rotation point, at least one seat rotation point and at least one link rotation point are selectively positioned such that the radial distance between the resistance pad and the LRC accommodates users of varying size, and the range of said radial distance between the resistance pad and the LRC over the repetition cycle is minimized.
 8. A machine according to claim 2, wherein the LRC corresponds to the approximate center of rotation of the lower five vertebrae of a user positioned on the seat.
 9. A machine according to claim 1, wherein the resistance pad engages the upper back of the user.
 10. A machine according to claim 1, further comprising: a locking mechanism for selectively adjusting the initial angle of the resistance arm relative to the base frame at the beginning of a repetition cycle; and wherein the resistance arm further comprises: a first end coupled to the resistance pad; and a second end coupled to the locking mechanism; the first rotation point of the resistance arm positioned between the first and second end of the resistance arm.
 11. A machine according to claim 10, wherein the locking mechanism further adjusts the angular range of the resistance arm during a repetition cycle.
 12. A machine according to claim 11, wherein the locking mechanism disengages the machine resistance while adjusting the initial angle of the resistance arm to accommodate users of varying flexibility entering the machine.
 13. A machine according to claim 12, wherein the locking mechanism comprises a hydraulic cylinder.
 14. A machine according to claim 1, wherein the seat frame member comprises a first end adjacent the seat, a second end coupled to a foot board for mounting the user's feet during operation of the machine, and a first seat rotation point adjacent the second end.
 15. A machine according to claim 14, wherein the seat frame member further comprises a second seat rotation point between the first and second end, along an underside of the seat frame member.
 16. A machine according to claim 15, further comprising a lifting arm having a first end coupled to the resistance arm first rotation point and a second end rotatably coupled to the second seat rotation point of the seat frame member.
 17. A machine according to claim 16, wherein the base frame comprises: at least one side bar having a first end integral with the base frame and a second end coupled to the first rotation point of the resistance arm and further coupled to the first end of the lifting arm; and at least one stand for supporting the seat frame member adjacent the second end of the lifting arm prior to beginning the repetition cycle.
 18. A machine according to claim 10, wherein the resistance pad further includes a pair of handles coupled to the first end of the resistance arm to be grasped by the user during the repetition cycle.
 19. A machine according to claim 1, further comprising at least one knee restraint coupled to the seat frame member for restraining the user's knees and isolating the pelvis while using the machine.
 20. A machine according to claim 19, wherein the at least one knee restraint further comprises: an adjustable knee bar for adjustably positioning the knee restraint, and; a locking device for securing the knee restraint in contact with the user's knees.
 21. A method for assembling a machine for exercising the muscles of the lower back, the method comprising: forming a base frame; rotatably coupling a resistance arm including a resistance pad to be engaged by the user to the base frame at a first rotation point, the resistance arm having a center of rotation about said first rotation point; rotatably coupling a seat frame member carrying a seat to the base frame at least one seat rotation point, the seat frame member having a center of rotation about each of said at least one seat rotation point; said resistance arm and seat frame member rotated in opposite directions during a repetition cycle about the respective first rotation point and at least one seat rotation point.
 22. The method according to claim 21, wherein the seat includes a base and a back for defining a lumbar rotation center (LRC) fixed relative to the seat, the LRC positioned above the base and forward from the back; and wherein the resistance pad center of rotation substantially coincides with the LRC.
 23. The method according to claim 22, wherein the radial distance between the resistance pad and the LRC accommodates users of varying size, and the range of said radial distance between the resistance pad and the LRC over the repetition cycle is minimized.
 24. A method according to claim 22, wherein the base frame extends the base of the machine; and further comprising: coupling at least one forward link from the base frame to the seat frame member adjacent a front area of the machine; said at least one forward link comprising at least one link rotation point, including at least one of said at least one seat rotation point.
 25. The method according to claim 24, wherein said at least one forward link comprises a top end and a bottom end, and wherein the one of said at least one seat rotation point is adjacent the top end of the at least one forward link.
 26. The method according to claim 25, wherein said at least one forward link includes a rotation point adjacent the bottom end for rotatably connecting the at least one forward link to the machine base.
 27. The method according to claim 26, wherein the first rotation point, at least one seat rotation point and at least one link rotation point are selectively positioned such that the radial distance between the resistance pad and the LRC accommodates users of varying size, and the range of said radial distance between the resistance pad and the LRC over the repetition cycle is minimized.
 28. The method according to claim 21, further comprising: forming a locking mechanism for selectively adjusting the initial angle of the resistance arm relative to the base frame at the beginning of a repetition cycle; and wherein coupling the resistance arm further comprises forming a first end coupled to the resistance pad; and forming a second end coupled to the locking mechanism; the first rotation point of the resistance arm located between the first and second end.
 29. The method according to claim 28, wherein forming the locking mechanism further comprises forming a hydraulic cylinder.
 30. The method according to claim 21, wherein forming the seat frame member further comprises: forming a first end adjacent the seat; forming a second end coupled to a foot board for mounting the user's feet during operation of the machine, and; positioning a first seat rotation point adjacent the second end.
 31. A method according to claim 21, wherein forming the base frame comprises: forming a side bar having a first end integral with the machine base and a second end rotatably coupled to the first rotation point of the resistance arm and further coupled to the first end of the lifting arm; and forming a stand for supporting the seat frame member adjacent the second end of the lifting arm prior to beginning the repetition cycle. 